In vivo models are critical to the understanding of pathogenic mechanisms operating in viral diseases, and for evaluation of therapeutic approaches to combat these diseases. KSHV has been isolated from B cell derived lymphomas found in patients with AIDS, termed PEL and MCD. There is an incomplete understanding of the initial cellular targets of KSHV infection and cells that contribute to viral dissemination and latency in vivo. We speculate that KSHV infection of progenitor B cells is key process in the initiation of oncogenesis. KSHV genomic sequences have been detected in hematopoietic progenitor (CD34+) cells from KS patients. We have demonstrated that KSHV infects human CD34+ cells and that viral gene expression is maintained in CFU-GM clonogenic colonies derived from the differentiation of these cells in vitro. KSHV genomic DNA and LANA-1 expression was detected in human (CD14+) monocytes and in B lymphocytes from NOD/SCID-hu chimeric mice following reconstitution of lymphopoiesis with infected human CD34+ cells. Although this model system is not perfectly representative of normal human hematopoiesis and/or all aspects of KSHV infection, the combination of KSHV persistence in NOD/SCID-hu mice and infection of CD34+ cells provides an experimental system in which to address many of the issues of KSHV replication, latency and pathobiology in vivo. This novel animal model will be employed to assay the efficacy of AZT and IFN-alpha in suppressing KSHV infection in vivo. This proposal aims to further refine and develop the NOD/SCID-hu mouse model of KSHV infection and to better understand the role of KSHV infection in CD34+ hematopoietic progenitor cells. Specific Aims are: (1) Evaluate, optimize and assess the effects of KSHV and rKSHV.219 de novo infection of CD34+ cells in vitro. Determine if KSHV establishes a latent infection in human CD34+ hematopoietic progenitor cells and characterize the role of viral infection on suppression of hematopoiesis. (2) Determine KSHV cell tropism and tumorigenic potential by immune reconstitution of NOD/SCID mice with CD34+ HPCs infected with KSHV and rKSHV.219. Evaluate and characterize the effect of KSHV/HHV-8 infection on hematopoiesis in vivo. (3) Determine if AZT and IFNalpha induces apoptosis in primary hematopoietic cells infected with rKSHV.219. Develop the NOD/SCID-hu mouse as a pre-clinical model for therapeutic intervention to inhibit KSHV replication. [unreadable] [unreadable]